This invention concerns forming of sheet material in a press, as by the use of dies. In such operations, it is sometimes necessary to perform additional steps on a workpiece after it is formed, such as piercing holes, forming flanges, etc.
This is traditionally done by transferring the workpiece into an additional die set configured to perform the secondary operation.
Such an approach is costly in terms of requiring additional dies, and also in the handling involved in moving the workpiece into a second die set.
While it would be possible to utilize separate power cylinders and tooling in the initial die for this purpose set, this approach would require external hydraulic and/or pneumatic lines to be installed, increasing the cost of the installation as well as the maintenance requirements of the equipment.
Another approach, as suggested in U.S. Pat. No. 3,858,427, is a mechanical cam operated secondary tooling driven by the press motion. This approach somewhat limits the operations able to be performed since the cam is directly controlled by the press motion. Also, the mechanism must be custom designed for each application, increasing its costs.